Constructing binder-free 3D thermal networks with hexagonal boron nitride of varying sizes to enhance polydimethylsiloxane composites: a comparative study†

As electronic devices become more compact and power-dense, the demand for efficient thermal management materials continues to rise. To address the common issues in conventional thermally conductive composites—namely, poor filler dispersion, high interfacial thermal resistance caused by binders, and complex fabrication processes—this study proposes a novel strategy for constructing binder-free three-dimensional hexagonal boron nitride thermal networks (3D BN) within a polydimethylsiloxane (PDMS) matrix. By leveraging the decomposition behavior of ammonium bicarbonate (NH₄HCO₃), this approach enables the fabrication of composites with enhanced thermal conductivity and simplified processing. The 3D BN/PDMS composites were prepared via a straightforward process involving blending, cold pressing, drying, and vacuum impregnation. Characterization and testing reveal that the 3D BN thermal network and BN particle size are critical factors influencing the composites' TCs. The resulting 3D BN/PDMS composites exhibit an outstanding TC of 3.889 W m⁻¹ K⁻¹ when the BN particle size is 20 μm and the filler content is 40.70 vol%. This study offers a novel approach to designing and developing high-performance thermally conductive composites, with significant potential for practical applications.